1. Filed of the Invention
The present invention relates to a semiconductor device such as an active semiconductor device having at least three terminals, a semiconductor device of an integrated circuit form and a three-dimensional semiconductor device, including a communicating device for readily and exactly performing a signal communication between front and rear surfaces of a semiconductor substrate therethrough.
2. Description of the Background Art
In a semiconductor substrate including conventional semiconductor devices or an integrated circuit (IC) having the same, there is usually provided with one terminal for a drain or the like of one of devices on the rear surface and are, in turn, provided with other terminals for the devices on the front main surface in the form of metallic contact terminals or electrodes at an insulating oxide film.
For instance, IEEE Power Electronics Specialists Conference Record, 1985, pp 229-233, discloses a cross section of a power MOSFET having a protector function therein. In this case, various elements or devices are formed in the front main surface of the semiconductor substrate, and almost all of their electrode terminals are formed on the front main surface, while only one output drain terminal is formed on the rear surface.
In such a conventional case, the rear surface of the semiconductor substrate is contacted with a mounting substrate, and it is enough to provide only one voltage source to the semiconductor substrate. Further, even when the front main surface including the semiconductor IC is bonded to the mounting substrate facing thereto, it is unnecessary to provide a plurality of electrodes independently for applying different voltages on the rear surface of the semiconductor substrate having a certain thickness. Hence, it is not considered to supply a plurality of different voltages or currents from the rear surface to the front main surface of the semiconductor substrate therethrough while being isolated from one another.
In a conventional three-dimensional laminated semiconductor substrate structure, as disclosed in Nikkei Micro Device, 1985, July, pp 175-192, the signal communication between the front and rear surfaces of the semiconductor substrate on which various devices or ICs are formed on the front surface, is developed insufficiently. Accordingly, when two laminated semiconductor substrates are further laminated one on another, the desired electrode portions of the two substrates are positioned and are securely connected in order to carry out the signal communication between the two substrates. However, in this case, it is rather difficult to provide wirings for connecting the front and rear surfaces of the substrates.
Another conventional three-dimensional laminated semiconductor substrate structure is prepared by stacking a plurality of semiconductor substrates, as disclosed in IEEE Computer, 1984, January, p 69, by Jan. Grinberg. In this embodiment, an ohmic wiring penetrating the substrate is produced by forming a p.sup.+ -type region passing through an n-type semiconductor substrate using a p-type aluminum dopant diffusion based on the heat transfer diffusion by the aluminum dot. The interconnection between the two substrates is realized by contacting cross-linked two metallic microbridges for connection.
In this case, however, since the feed through portion is composed of the p.sup.+ -type portion of the P.sup.+ N junction and a separation of P.sup.+ N junction is used, it is difficult to control a distribution capacity due to the PN junction and upper and lower resistance values of the p.sup.+ -type portion. Further, since the microbridges are not securely connected to each other, it is insufficient in stability of the mechanical structure for linking the two substrates, and its sufficient or ideal isolation from the other portions can not be performed.